.wrapper{
    position: relative;
    left: 500px;
    top: 200px;
    width: 500px;
    height: 300px;
    text-align:center;
}
.tu{
    width: 300px;
    height: 200px;
    text-align:center;
}
.button{
    text-align:center;
}
.b{
    width: 100px;
    height: 25px;
    background:linear-gradient(to right,rgb(0, 255, 149) 0%,rgb(90, 163, 205) 100%);
    border: 0px;
}